Electrical circuit breakers commonly include toggle switches for controlling the power delivered to particular circuits. Typically, the individual circuit breakers for several branch circuits are mounted in a compact array within a single housing.
In a circuit breaker of this kind, a recess is conventionally formed in each side of the switch handle. The usual recess extends perpendicularly with respect to the plane defined by the pivoting of the handle. Commonly, a switch handle has two such recesses, one on each side, separated by a web.
A ganged switch has a gang of two or more switch bodies and a handle assembly including two or more handles extending from the ganged switch body and joined by a crossbar.
A safety problem arises when the switch of a circuit breaker which controls a remote circuit is turned off so the circuit can be worked on. If one worker throws the circuit breaker switch, then goes to the remote circuit to work, others may be unaware that the corresponding circuit is being worked upon, and may turn the switch back on. The worker who is in contact with the circuit may be severely injured as a result.
Other problems can arise if a switch which is meant to stay on is turned off inadvertently. For example, if a switch controlling the power to a heating unit of a building is shut off inadvertently, the water in pipes in the building may freeze on a cold night.
Lockouts of various kinds have been physically attached to a switch or valve, and particularly to a circuit breaker switch, to maintain the handle of the switch in one state. Lockouts have often required permanent installation of special parts or other modifications of the switch body, which are undesirable (whether because work is required to install such a lockout or because installation may damage the circuit breaker or require the electrical service to the panel including the switch to be interrupted).
Other lockouts have parts which are inserted at least partially into the switch body. Such parts, and particularly electrically conductive parts, might themselves present an electrical shock hazard.